1. Field of the Invention
The present invention relates to an image processing apparatus and an endoscope system, and more particularly to an image processing apparatus and an endoscope system which are configured to display a medical image obtained by picking up an image in a subject.
2. Description of the Related Art
Conventionally, various less-invasive examinations and surgeries using an endoscope have been performed in medical fields. A surgeon inserts an endoscope into a body cavity, to observe an image of a subject picked up by an image pickup apparatus provided at a distal end portion of an endoscope insertion portion, and is capable of performing treatment on a lesion part using a treatment instrument inserted in a treatment instrument channel, as needed. A surgery using an endoscope has an advantage of low physical burden on a patient, because there is no need for opening the abdomen.
An endoscope apparatus is configured by including an endoscope, an image processing apparatus connected to the endoscope, and an observation monitor. An image of a lesion part is picked up by an image pickup device provided at a distal end portion of an endoscope insertion portion and the picked-up image is displayed on the monitor. A surgeon can perform diagnosis or a necessary treatment while viewing the image displayed on the monitor.
Recently, also an endoscope apparatus which displays capillary vessels under the surface of a living tissue of a subject using narrow-band light has been developed. Such an endoscope apparatus irradiates a subject with illumination light of predetermined narrow bands to obtain images in the respective narrow bands from the light reflected from the subject, or irradiates the subject with illumination light which is white light to obtain predetermined narrow-band images by performing a spectral estimation processing on the image of the light reflected from the subject, thereby allowing the capillary vessels to be displayed.
In addition, as disclosed in Japanese Patent Application Laid-Open Publication No. 2000-148987, for example, also an image processing apparatus has been proposed, which extracts a desired frequency component from an RGB image and changes a signal level of the extracted frequency component such that a microstructure or a subtle change in a color tone of a surface of mucosa can be clearly observed.
Furthermore, as an endoscope apparatus, also an infrared endoscope apparatus has been proposed, which is capable of observing blood vessels inside a subject by injecting indocyanine green (ICG) having a characteristic of absorption peak in near-infrared light of wavelength near 805 nm into the blood of a patient as medicinal agent and irradiating the subject with infrared lights of wavelengths near 805 nm and near 930 nm from a light source apparatus in a time divisional manner, for example.